Apparatus for applying sealing strips to containers



July 28, 1942. w JOPLIN APPARATUS FOR APPLYING A SEALING STRIP TO A CONTAINER Filed July 14, 1939 Gau uin Patentca.

APPARATUS FOR APPLYING SEALING STRIPS T CONTAINERS William A. Joplin, Wollaston, Mass., assignor to Pneumatic Scale Corporation, Limited, Quincy,

Mass, i corporation of Massachusetts Application July 14, 1939, Serial No. 284,408

(Cl. 216-21) I 2 Claims.

This invention relates to apparatus for applying a sealing strip to the top of a container.

The invention has for an object to provide novel apparatus for automatically applying a sealing strip to the top of a container, and particularly to the top of a container such as a paper bag having a top closure formed by folding and overfolding the closed mouth portion of the container in a simple and practical manner whereby the overfolded top closure is retained in its folded condition by said sealing strip.

With this general object in view and such others as may hereinafter appear, the invention strip to the top of a container, and in the various structures, arrangements and combinations of parts hereinafter described and particularly defined in the claims at the end of this specification.

In the drawing illustrating the preferred embodiment of the invention, Fig. 1 is a more or less diagrammatic view illustrating the present apparatus for applying a sealing strip to the top of a container in accordance with the invention; Fig. 2 is an enlarged cross-sectional view of a strip of the present sealing material: Fig. 3 is a cross-sectional view taken through the heat applying unit to be described; and Fig. 4 is a perspective view of the top of a container showing the applied sealing strip.

In general, the present invention contemplates apparatus for applying a sealing strip to the top of a filled container such as a paper bag to secure the loosely folded portions of the top fold down onto the top of the container. In the preferred embodiment of the invention, the sealing strip comprises a tape, preferably a paper strip, to which a coating of thermo-plastic adhesive has beenpreviously applied and permitted to dry, such adhesively coated material being commercially available upon the market. Provision is made in accordance with the present invention for feeding and cutting of! a strip of the tape and for applying the latter to the top of the container with the application of heat to render adhesive-the thermo-plastic coating of the tape and to cause the strip to adhere to the folded over portions on the top of the container when the adhesive is again cooled. Provision is made for retaining the strip in engagement with the container while the adhesive is cooling in order to insure a firm seal for the top closure.

Prior to the present invention, the adhesive has been applied in a liquid condition, either to the tape or to the portion consists in the apparatus for applying a sealing of the container to tainers. Thus,

which the tape was to be applied. In the present apparatus, the tape applying operation is simplified and the necessity for adhesive applying mechanism is eliminated. I

Referring now to the drawing, in represents a horizontally disposed and continuously moving conveyor chain provided with a plurality of spaced container engaging members i2 which are arranged to engage and convey successive containers l3 through the tape applying apparatus, as the containers are delivered thereto by a belt conveyor M. The belt conveyor i4 which runs over a pulley I! at one end may convey the containers from filling and top closing machines, not shown, so that when the containers are received by the container engaging members i2 they are already filled and have been provided with a top closure indicated generally at i6 formed by folding and overfolding'the mouth portion of the container.

During their travel through the machine, the containers ii are supported upon a lower guide rail I8 and the top closure i6 is retained in its folded down condition by a top rail 20. disposed adjacent the tape applying mechanism, as will be described.

As diagrammatically illustrated in Fig. 1, provision is made for feeding a'web or strip 22 of the sealing tape into position to be applied to the top of the container and for cutting oil a predetermined length of the tape to be applied. Such strip feed and cut-off mechanism may and preferably will comprise an intermittently driven feed roll 24 arranged to be rotated in timed relation to the continuously moving containers l3. The feed roll 24, operating in cooperation with an idler roll 26 is arranged to withdraw the tape 22 from a roll 2| thereof, over idler rolls 30, 32 and between upper and lower guides 34, 36 into a position to be cut oil by a reciprocatingly mounted knife 40. The knife 40 is arranged to cooperate with a stationary shearing edge 42 formed on the lower guide plate 36.

As illustrated in Fig. 1, the guides 34, 36 are disposed at an angle with respect to the top of the containers II and, in the operation of the mechanism, a strip is fed into a position extending into the path of an oncoming container. When the leading edge of the container engages the extended strip, the latter is pressed into engagement with the top of the container by the foremost roll of a plurality of stationary heated rollers 44 arranged adiacent the guide members and in operative relation to the top of the conit will be seen that in the opera- 2 tion of the device, the strip is initially grasped between the bite of the foremost roller 44 and the corner of the filled container, the reciprocatory knife ll operating to cut oil a predetermined length Just as thestrip is grasped, and upon continued movement of the container, the strip is pulled from the guides'and pressed into engagement with the container.

.As hereinbefore described-the scaling tape 22 is provided with a film-of thermo-plastic material 23 which is commercially available in roll form and which is rendered adhesive by the ap- Plication :of heat. .As-herein shown. the rollers 44 are preferably heated electrically by heating elements comprising the resistance coils I! which are positioned in housings 48, II as illustrated in cross-section in Fig. 3. The housings i, II are secured to a tie bar If in spaced relation and are arranged to support the rollers 44 therebetween.

The rollers N are heated by contact with the housings II, II, and as herein shown, the housings are surrounded by insulating plates ll, forming in effect an oven which tends to retain the heat around the rollers. The resistance coils 46, mounted in the housings are supplied withelectrical energy from anyconvenient source, through the leads, II and II are shown in Fig. l. The circuit may be supplied with the controls such as a rheostat and a thermostat, not shown-,in order to control the degree of heat required. In' practice, the thermo plastic tape may be obtained in different grades, becoming adhesive at different temperatures ranging from I 300 degrees to'650 degrees F. and the grade preferably employed in the present instance is rendered adhesive at temperatures between 600 degrees and 650 degrees F. As shown in Fig. 3, the unit may be enclosed within a protective covering member 62.

In order to cause the strip to firmly engage the top of the container and insure holding the overfolded'portions of the top closure down onto the adjacent fiat portion of the container, the rollers 44 are shaped to conform to the irregular surface presented by the folded down top closure II as shown. Thus,'one

portion 45 of each roller is turned down to conform to the raised portion of the overfolded closure while the portion 41 is of larger diameter and slightly tapered, as shown, to conform to the depressed portion of the fiat surface of the container. In the operation of the machine, the continuously moving containers. with the sealing strips applied pass under successive heating rollers 44 whereby the thermo-plastic coating is rendered adhesive and the strips pressed into firm engagement with the top of the folded down of sealing tapeclosure and the fiat topof the filled container. Thereafter, as illustrated in Fig. 1, the containers pass under a plurality of unheated pressure rollers 84 while theadhesively sealed top is cooling, in order to firmly set the seal.

From the description thus far, it will be observed that the present apparatus for securing the overfolded portions of the top closure of a container enables the operation to be accomplished in a convenient and economical manner,

While the preferred embodiment of the invention has been herein illustrated and described, it will be understood that the invention may be embodied in other forms within the scope of the following claims.

Having thus described the invention, what is claimed is: I

1. In apparatus for securing the folded down top closure of a container including conveying mechanism for containers and cutting means for forming froma source of supply an individual strip of thermo-plastic sealing tape corresponding to the length of the surface to which it is to-be applied, the combination, of means for applying said strip of thermo-plastic tape to the folded down top closure of a container comprising a housing disposed along said conveyor succeeding and adjacent to said cutting means, heating means carried by the side walls of said housing, a series of heated rollers supported in said housing between the side walls thereof and in heat exhange relationship with said heating means, the said housing serving as an oven to confine heat a said rollers, the roller closest to said cutting means being in position to grasp the cut strip of thermoplastic tape and press the same into engagement with the folded down top closure of a container as it passes said roller,

the-remaining rollers supported in said housing between the strip and the top of a container, and

a series of unheated rollers outside said housing and succeeding said heated rollers along said conveyor, the said unheated rollers being positioned to successively apply pressure to the strip adhering to the top of a container to set the adhesive.

2. The apparatus of claim '1 wherein the heated rollers are provided with stepped periphcries conforming substantially to the irregular shape of the folded down top closure of a container whereby heat and pressure are uniformly applied to the sealing strip.

WILLIAM A. JOPLINr 

